Psoriatic arthritis incidence and prevalence trajectory in Poland-public-payer, national-level, long-term data

To estimate the actual incidence and prevalence of psoriatic arthritis (PsA) within a 9-year timeframe in Poland. Patients were defined as having PsA if they had at least two visits more than 90 days apart with ICD-10 codes M07.0, M07.1, M07.2, M07.3, or L40.5 and filled at least one reimbursed prescription for peripheral or axial PsA-specific treatments during this period (including methotrexate, sulfasalazine, ciclosporin, leflunomide, biologics, targeted synthetic drugs, or non-steroidal anti-inflammatory drugs). Data was obtained from the nationwide public payer database, considering gender, age, and region of residence. We observed an incidence rate of 1.1 per 100,000 inhabitants in 2021, compared to 13.2 in 2013. Regarding the age of the first diagnosis, the peak incidence rate decreased, with a more pronounced decline in men. The prevalence of PsA rose from 72.5 individuals per 100,000 in 2013 to 95.5 in 2021, representing approximately 0.1% of the total population in Poland, with a significant predominance of women among patients over 55 years of age. The decline in PsA incidence may be influenced by a strict case definition and improved access to treatment. Higher prevalence in older women suggests potential gender-related differences. The lower peak incidence and younger diagnosis age in men raise questions about whether lower PsA prevalence in older males is linked to higher mortality due to longer disease duration and comorbidities. Further research is needed to clarify these findings.